Power transmission system

ABSTRACT

A power transmission assembly includes a base, a rotating frame rotatably coupled to the base and configured to rotate about an axis, an output shaft coupled to the rotating frame, a weight selectively repositionable relative to the rotating frame, and a weight actuator configured to reposition the weight relative to the rotating frame to move the weight from a subtraction position located at a first height to an addition position located at a second height. The second height is greater than the first height such that a gravitational force on the weight drives the rotating frame to rotate about the axis and drive the output shaft.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/437,613, filed Sep. 9, 2021, which is a 371 national stage ofInternational Patent Application No. PCT/US2021/033426, filed May 20,2021, which claims the benefit of U.S. Provisional Patent ApplicationNo. 63/031,126, filed May 28, 2020, all of which are incorporated hereinby reference in their entireties.

BACKGROUND

The present disclosure relates generally to power transmissions. Morespecifically, the present disclosure relates to power transmissions thatreceive a first type of mechanical energy (e.g., linear movement of anobject) as an input and output a second type of mechanical energy (e.g.,rotational mechanical energy).

SUMMARY

At least one embodiment relates to a power transmission assemblyincluding a base, a rotating frame rotatably coupled to the base andconfigured to rotate about an axis, an output shaft coupled to therotating frame, a weight selectively repositionable relative to therotating frame, and a weight actuator configured to reposition theweight relative to the rotating frame to move the weight from asubtraction position located at a first height to an addition positionlocated at a second height. The second height is greater than the firstheight such that a gravitational force on the weight drives the rotatingframe to rotate about the axis and drive the output shaft.

This summary is illustrative only and is not intended to be in any waylimiting. Other aspects, inventive features, and advantages of thedevices or processes described herein will become apparent in thedetailed description set forth herein, taken in conjunction with theaccompanying figures, wherein like reference numerals refer to likeelements.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a front view of a power transmission system, according tovarious exemplary embodiments.

FIG. 2 is a right side view of the power transmission system of FIG. 1 .

FIG. 3 is front view of the power transmission system of FIG. 1 in afirst position.

FIG. 4 is front view of the power transmission system of FIG. 1 in asecond position.

FIG. 5 is front view of the power transmission system of FIG. 1 in athird position.

FIG. 6 is front view of the power transmission system of FIG. 1 in afourth position.

FIG. 7 is a block diagram of a control system for the power transmissionsystem of FIG. 1 , according to an exemplary embodiment.

FIG. 8 is a top view of a system including several of the powertransmission systems of FIG. 1 , according to an exemplary embodiment.

FIG. 9 is a front view the power transmission system of FIG. 1 ,according to an exemplary embodiment.

FIG. 10 is a front view the power transmission system of FIG. 1 ,according to another exemplary embodiment.

FIG. 11 is a front view the power transmission system of FIG. 1 ,according to another exemplary embodiment.

FIG. 12 is a top view of a power transmission system, according to anexemplary embodiment.

FIG. 13 is a front view of the power transmission system of FIG. 12 .

DETAILED DESCRIPTION

Before turning to the figures, which illustrate certain exemplaryembodiments in detail, it should be understood that the presentdisclosure is not limited to the details or methodology set forth in thedescription or illustrated in the figures. It should also be understoodthat the terminology used herein is for the purpose of description onlyand should not be regarded as limiting.

Referring generally to the figures, a power transmission is shownaccording to various exemplary embodiments. The power transmissionincludes a rotating frame or wheel that is rotatably coupled to a base.The wheel rotates about a substantially horizontal axis of rotation. Insome embodiments, the wheel is coupled to an electromagnetic device suchthat rotation of the wheel drives the electromagnetic device to generateelectrical energy. One or more weights are selectively repositionablerelative to the wheel. Specifically, the weights are moved relative tothe wheel by a weight actuator to drive rotation of the wheel.

According to one embodiment, the power transmission operates accordingto a cycle. At the beginning of the cycle, the weight is (a) coupled tothe wheel, (b) offset a distance from the axis of rotation, and (c)located at an addition position relative to the wheel. The additionposition is located at a first, elevated height. Gravity imparts adownward force on the weight. Due to the offset distance of the weightfrom the axis of rotation, the force of gravity imparts a moment load onthe wheel, driving the wheel to rotate about the axis of rotation. Asthe wheel rotates, the weight moves downward, toward a subtractionposition having a second height that is lower than the first height.When the wheel has rotated sufficiently for the weight to have reachedthe subtraction position, the weight actuator engages the weight, movingthe weight relative to the wheel. The weight actuator returns the weightto the addition position where the weight is again coupled to the wheel,completing the cycle of operation. The cycle may be repeated to continuerotation of the wheel.

Referring to FIGS. 1 and 2 , a power transmission system, wheelassembly, power transmission assembly, power transmission, powerconversion assembly, or generator, is shown as system 10 according to anexemplary embodiment. The system 10 includes a chassis, frame, or baseassembly, shown as base 20. The base 20 is configured to support thevarious components of the system 10. The base 20 includes a bottomportion, base portion, or horizontal portion, shown as foot 22 and a topportion, upper portion, or vertical portion, shown as support wall 24,that is fixedly coupled to the foot 22 and extends upward from the foot22. The support wall 24 defines an aperture or passage, shown as outputshaft passage 26, that extends through the support wall 24. The shaftpassage 26 may be at least partially defined by a bushing or bearingthat facilitates rotation of a shaft extending through the shaft passage26 relative to the support wall 24.

The system 10 further includes a wheel, rotating frame, or rotatingsupport structure, shown as wheel 30. The wheel 30 is fixedly coupled toa shaft, shown as output shaft 32. The output shaft 32 extends throughthe shaft passage 26, such that the output shaft 32 rotatably couplesthe wheel 30 to the base 20. The wheel 30 rotates about an axis ofrotation, shown as axis 34. The axis 34 extends along the output shaft32 (e.g., is centered about the output shaft 32). In some embodiments,the axis 34 extends substantially horizontally. In such embodiments, thewheel 30 rotates within a substantially vertical plane (e.g., a planeperpendicular to the horizontal axis 34).

The system 10 includes one or more weights 40 that are coupled to thewheel 30. Specifically, in the embodiment shown in FIG. 1 , the weights40 include a weight 40A, a weight 40B, a weight 40C, and a weight 40D.Each of the weights 40 may have the same mass, or one or more of theweights 40 may have different masses. Each weight 40 has a center ofgravity C that is offset from a distance D from the axis 34. As shown inFIG. 1 , the distance D is equal for each of the weights 40. In otherembodiments, the weights 40 are positioned at different distances fromthe axis 34 such that the distance D varies for one or more of theweights 40. The center of gravity C of each weight 40 is positioned at avertical position or height H. As shown, each height is measuredrelative to the bottom of the base 20. In other embodiments, the heightH is measured from another location. The center of gravity C of eachweight 40 is located at an angular position Θ that corresponds to theheight H of the center of gravity C. As shown, the angular position Θ is0 degrees when the corresponding height H of the weight 40 is maximized(e.g., at top dead center), and the angular position Θ is 180 degreeswhen the corresponding height H of the weight 40 is minimized (e.g., atbottom dead center). In other embodiments, the angular position Θ ofeach weight 40 is otherwise measured.

In some embodiments, the weights 40 are selectively repositionablerelative to the wheel 30. In some embodiments, the weights 40 areselectively coupled to the wheel 30 such that the weights 40 aredecoupled from the wheel 30 when the weights 40 are repositionedrelative to the wheel 30. By way of example, the weights 40 may bedecoupled (e.g., by disconnecting a latch or other mechanical coupler,by disconnecting the power supply to an electromagnet, etc.). In otherembodiments, the weights 40 are slidably coupled to the wheel 30 suchthat the weights remain coupled to the wheel 30 while the weights 40 arerepositioned relative to the wheel 30. By way of example, the weights 40may be slidably coupled to a track positioned on the wheel 30 such thatthe weights 40 travel along the track.

Referring to FIG. 2 , the system 10 includes an actuator, shown asweight actuator 50, that is configured to reposition the weights 40relative to the wheel 30. In some embodiments, the weight actuator 50includes a weight interface or end effector, shown as interface 52, anda height actuator or weight shifter, shown as lift 54. The interface 52is configured to couple (e.g., selectively, continuously, permanently,etc.) the weights 40 to the weight actuator 50. With the weights 40coupled to the interface 52, the lift 54 is configured providemechanical energy to raise the weights 40 relative to the wheel 30.Accordingly, the weight actuator 50 is configured to lift or raise theweights 40 from a first, low elevation to a second, greater elevation.By way of example, the weight actuator 50 may raise the weight 40A froma height H₁ of 1 ft to a height H₁ of 5 ft.

Referring to FIGS. 3-6 , an exemplary portion of a cycle of operation ofthe system 10 is shown according to an exemplary embodiment. In FIG. 3 ,the weights 40 are all coupled to the wheel 30. The weights 40 are allpositioned on the wheel 30 such that the centers of gravity C of each ofthe weights 40 are all located on one side of the wheel (e.g.,0°<Θ<180°). Gravity applies a downward gravitational force G onto eachweight 40 at the corresponding center of gravity C. Due to theseparation of the centers of gravity C from the axis 34, thegravitational force G on each weight 40 imparts a moment loading on thewheel 30, driving the wheel 30 to rotate in a first direction (e.g.,counterclockwise as shown in FIG. 3 ). As the wheel 30 rotates, thehorizontal distance between each center of gravity C and the axis 34(i.e., the length of the moment arm) varies, varying the moment loadimparted by each weight 40. The moment load M exerted by a given weight40 can be calculated using the following equation:M=GD sin θ=mgD sin θ  (1)where G is the gravitational force on a given weight 40, D is thedistance of the weight 40 from the axis 34, Θ is the angular position ofthe weight 40, m is the mass of the weight 40, and g is the accelerationdue to gravity experienced by the weight 40 (e.g., 9.81 m/s²). Themoment effect of each weight 40 can be calculated separately andcombined to determine the total moment load of the weights 40 on thewheel 30.

Because each of the weights 40 are located on the left side of the wheel30, the sum of the moment loads of the weights 40 is positive, and thewheel 30 is driven to rotate in the first direction. As the wheel 30rotates, the weights 40 all move downward. As shown in FIG. 4 , theweight 40D eventually reaches a position or range of positions (e.g., abottom position or subtraction position), shown as subtraction position60. The subtraction position 60 is fixed in space (e.g., relative to thebase 20). In some embodiments, the subtraction position 60 correspondsto a bottom dead center position of the weight 40D (i.e., where theangular position Θ of the weight 40D is 180 degrees), such that theheight H of the weight 40D would begin increasing if the wheel 30rotated further in the first direction. In other embodiments, thesubtraction position corresponds to a position of the weight 40D abovebottom dead center (e.g., where the angular position Θ of the weight 40Dis less than 180 degrees).

When the weight 40D reaches the subtraction position 60, the interface52 engages the weight 40D, and the lift 54 applies an upward force tothe weight 40D, lifting the weight 40D. The weight actuator 50 may liftthe weight 40D straight upward or along a path that moves upward andlaterally (e.g., to avoid one or more obstacles). As shown in FIG. 5 ,the weight actuator 50 moves the weight 40D to an intermediate position62. In some embodiments, the weight 40D is slidably coupled to the wheel30 such that the weight 40D remains coupled to the wheel 30 while in theintermediate position 62. In other embodiments, the weight 40D isselectively coupled to the wheel 30, and the weight 40D is decoupledfrom and/or separated from the wheel 30 while in the intermediateposition 62.

As shown in FIG. 6 , the weight actuator 50 moves the weight 40D to aposition or range of positions (e.g., a top position or additionposition), shown as addition position 64. The addition position 64 isfixed in space (e.g., relative to the base 20). In some embodiments, theaddition position 64 corresponds to a top dead center position of theweight 40D (i.e., where the angular position Θ of the weight 40D is 0degrees), such that the height H of the weight 40D would begindecreasing if the wheel 30 rotated further in the first direction. Inother embodiments, the addition position 64 corresponds to a position ofthe weight 40D below top dead center (e.g., where the angular position Θof the weight 40D is greater than 0 degrees).

When the weight 40D reaches the addition position 64, the weight 40D isagain coupled (e.g., fixedly coupled, rotatably coupled, etc.) to thewheel 30 such that the weight 40D is again positioned at the distance Dfrom the axis 34. With the weight 40D coupled to the wheel 30, theweight 40D again moves with the wheel 30. As the wheel 30 continues torotate, the weight 40D moves downward until the weight 40D again reachesthe subtraction position 60, and the cycle of operation shown in FIGS.3-6 may be repeated to facilitate continuous rotation of the wheel 30.

The system 10 may also control the weight actuator 50 to lift the otherweights (e.g., weights 40A, 40B, and 40C) to the addition position 64 inresponse to the weight reaching the subtraction position 60. By way ofexample, when the weight 40C reaches the subtraction position 60, theweight actuator 50 may engage the weight 40C and lift the weight 40C tothe addition position 64 through the intermediate position 62. By way ofanother example, when the weight 40B reaches the subtraction position60, the weight actuator 50 may engage the weight 40B and lift the weight40B to the addition position 64 through the intermediate position 62. Byway of another example, when the weight 40A reaches the subtractionposition 60, the weight actuator 50 may engage the weight 40A and liftthe weight 40A to the addition position 64 through the intermediateposition 62. In this way, the system 10 maintains a cycle of operationthat continuously replaces each weight 40 at an elevated position suchthat each weight 40 continues to drive the wheel 30 over time.

By utilizing multiple repositionable weights 40, the moment load on thewheel 30 may be increased, increasing the output torque that the system10 is capable of delivering. Additionally, the use of multiple weights40 facilitates applying a more consistent torque to the wheel 30. As thewheel 30 rotates, the moment load imparted by each weight 40 varies both(a) due to the variation in the length of the moment arm of the weight40 as the wheel 30 rotates and (b) due to the reduction in torque whenthe weight 40 is being moved from the subtraction position 60 to theaddition position 64. Adding more weights 40 to the system 10 reducesthe effect of these variations in torque on the overall torqueexperienced by the wheel 30, as the torque provided by each weight 40then makes up a lesser portion of the overall torque. By way of example,in a system 10 that includes only the weight 40D, the wheel 30 mayexperience no torque when the weight 40D is being moved from thesubtraction position 60 to the addition position 64. However, in asystem 10 that includes both the weight 40B and the weight 40D, theweight 40B continues to impart a moment load on the wheel 30 while theweight 40D is being moved from the subtraction position 60 to theaddition position 64.

Referring again to FIG. 2 , the torque imparted on the wheel 30 by theweights 40 is transferred by the output shaft 32. As shown in FIG. 2 ,the output shaft 32 is coupled to a power take off (PTO) output, shownas PTO 70. Specifically, the output shaft 32 is shown as being directlycoupled to the PTO 70 such that the output shaft 32 drives the PTO 70.The output shaft 32 is coupled to an electromagnetic device ormotor/generator, shown as electric motor 72. Specifically, a shaft ofthe electric motor 72 is coupled to the output shaft 32 by a powertransmission (e.g., a gearbox, a chain and sprocket assembly, a belt andpulley assembly, a gear train, etc.), shown as belt 74. In otherembodiments, the electric motor 72 is directly coupled to the outputshaft 32. In other embodiments, the PTO 70 is coupled to the outputshaft 32 by the belt 74 or another type of power transmission. In otherembodiments, the PTO 70 and/or the electric motor 72 are omitted.

The PTO 70 may include one or more devices that receive and utilizerotational mechanical energy from the output shaft 32. The PTO 70 mayinclude one or more devices that convert rotational mechanical energy toanother form. By way of example, the PTO 70 may include a pump orcompressor that receives rotational mechanical energy and provides aflow of a pressurized fluid (e.g., a gas, a liquid, etc.). By way ofanother example, the PTO 70 may include a generator that receivesrotational mechanical energy and provides electrical energy. The PTO 70may include one or more devices that utilize rotational mechanicalenergy to perform one or more functions. By way of example, the PTO 70may include a wheel (e.g., as part of a drivetrain for a vehicle), aconveyor, an implement (e.g., a saw, a lathe, a mill, a washing machine,etc.), or another type of device.

The electric motor 72 may be configured to receive rotational mechanicalenergy and provide electrical energy. The electric motor 72 may providealternating current or direct current electrical energy. The electricmotor 72 may be configured to receive electrical energy and providerotational mechanical energy. By way of example, the electric motor 72may drive the wheel 30 and/or the PTO 70. Electrical energy provided(e.g., generated) by the electric motor 72 may be used to power anyfunctions of the system 10.

In some embodiments, the system 10 includes one or more energy storagedevices, shown as batteries 76. The batteries 76 may receive and storeelectrical energy provided by the electric motor 72. The batteries 76may provide stored electrical energy to power the electric motor 72. Thebatteries 76 may include one or more lithium ion batteries, lead acidbatteries, nickel metal hydride batteries, or other types of batteries.Additionally or alternatively, the system 10 may include another type ofenergy storage device, such as one or more capacitors.

In some embodiments, the system 10 includes one or more electricalloads, shown as loads 78. The loads 78 may be electrically coupled tothe electric motor 72 and/or the batteries 76. The loads 78 may beconfigured to consume electrical energy from the electric motor 72and/or the batteries 76. The loads 78 may additionally or alternativelybe configured to provide electrical energy to the electric motor and/orthe batteries 76. By way of example, the loads 78 may include electricmotors, heating elements, electronics (e.g., controllers, displays,etc.), or other electrical loads. By way of another example, the loads78 may include an electrical grid that consumes electrical energy fromthe system 10 and/or provides electrical energy to the system 10.

In some embodiments, it is advantageous to minimize the weight of thewheel 30 and maximize the weight of the weights 40. This arrangementmaximizes the amount of output power provided by the system 10 forweights of a given size while minimizing the energy required toaccelerate the wheel 30. In some embodiments, the wheel 30 includesrelatively lightweight materials, such as aluminum or bamboo. In someembodiments, the weights 40 include relatively dense materials, such aslead, mercury, steel, or iron.

The path along which the weights 40 move between the subtractionposition 60 and the addition position 64 may vary between differentembodiments. In some embodiments, the weights 40 move straight upward,along the side of the wheel 40 or through the center of the wheel. Insome embodiments, the path of the weights 40 curves such that themomentum of the weights 40 caused by spinning of the wheel 30 carriesthe weights 40 along the path. In some embodiments, the momentum of theweights 40 may carry the weights 40 up to 75% of the vertical distanceback to the addition point 60 without expending any additional energy.The weights 40 may enter the addition positon 64 from above, below, offrom the sides. By way of example, one weight 40 may be added from therear side, and the subsequent weight 40 may be added from the frontside.

The quantity, size, shape, and/or position of the weights 40 may varybetween different embodiments. By way of example, the weights 40 maytake up between 2% and 100% of the radius of the wheel 30. By way ofanother example, the system 10 may include two sets of weights 40, eachset of weights being at a different distance D from the axis 34. Theweights 40 may extend across a large portion (e.g., most, all, etc.) ofthe width of the wheel 30. By way of example, the weights 40 may have awidth of 1 ft, 2 ft, 3 ft, 5 ft, 10 ft, 15 ft, 20 ft, or more.

Although only one weight actuator 50 is shown in FIG. 2 , in someembodiments, the system 10 includes multiple weight actuators 50. By wayof example, one weight actuator 50 may be positioned on each side of thewheel 30 to facilitate rapid movement of the weights 40 without theweight actuators 50 interfering with one another. In such embodiments,the width of the wheel 30 may be increased, and the weights 40 may belocated at the center of the wheel 30 instead being of cantilevered offof one side of the wheel 30 to facilitate access from both sides of thewheel 30.

Referring to FIG. 7 , the system 10 includes a control system 100including processing circuitry, shown as controller 110. The controller110 includes a processor 112 and a memory device, shown as memory 114.The memory 114 may contain one or more instructions that are executed bythe processor 112 to control operation of the system 10. The controller110 is operatively coupled to the various components of the system 10.The controller 110 configured to receive information from variouscomponents of the system 10 and/or provide information (e.g., commands)to various components of the system 10.

In some embodiments, the controller 110 controls the weight actuator 50.Specifically, the controller 110 controls the weight actuator 50 to movethe weights 40 from the subtraction position 60 to the addition position64. By way of example, the controller 110 may control the interface 52to engage a weight 40 at the subtraction position 60, control the lift54 to raise the weight 40, and control the interface 52 to disengage theweight 40 from the lift 54 and/or couple the weight 40 to the wheel 30.The controller 110 may control the speed of the wheel 30 by varying thespeed at which the weight actuator 50 moves the weights 40.

In some embodiments, the controller 110 controls the electric motor 72and/or the batteries 76. By way of example, the controller 110 mayelectrically couple the electric motor 72 to the batteries 76 whilecontrolling the weight actuator 50 to drive the electric motor 72 suchthat the electric motor 72 provides electrical energy to charge thebatteries 76. By way of another example, the controller 110 mayelectrically couple the electric motor 72 to the batteries 76 andcontrol the batteries 76 to power the electric motor 72. By way ofanother example, the controller 110 may electrically couple the electricmotor 72 and/or the batteries 76 to the loads 78. The electric motor 72and/or the batteries 76 may provide electrical energy to the loads 78.In embodiments where the loads 78 includes an electrical grid, theelectrical grid may provide electrical energy to power the electricmotor 72 and/or charge the batteries 76.

In some embodiments, the control system 100 includes one or moresensors, shown as weight sensors 120, that are operatively coupled tothe controller 110. The weight sensors 120 are configured to providedata indicative of a position, orientation, or status (e.g., a filllevel) of one or more weights 40. By way of example, the weight sensors120 may include limit switches, proximity sensors, break beam sensors,or other sensors that provide data relating to a position of the weight40. By way of another example, the weight sensors 120 may include arotation sensor (e.g., an optical encoder or potentiometer, etc.) thatindicates an angular position of the wheel 30. The controller 110 mayutilize a predetermined relationship between the angular position of thewheel 30 and the positions of the weights 40 to determine the positionsof the weights 40.

Referring to FIG. 8 , a power transmission system, shown as system 200is shown according to an exemplary embodiment. The system 200illustrates how several of the system 10 may be combined with oneanother. As shown, the system 10 includes a first subassembly, shown aswheel assembly 210. The wheel assembly 210 includes three of the wheels30 arranged in series with one another. Specifically, three wheels 30are each coupled to one output shaft 32. In other embodiments, the wheelassembly 210 includes more or fewer wheels 30 arranged in series withone another (e.g., 3, 5, 10, 20, 30, 50, 100, or more wheels 30). Theoutput shaft 32 is rotatably supported by a pair of bases 20. The wheels30 all rotate about a common axis 34 that extends through the outputshaft 32. Each wheel 30 is driven by a corresponding weight actuator 50that repositions one or more weights 40 relative to the wheel 30. Themoment load of the weights 40 on each of the wheels 30 drives the outputshaft 32. The output shaft 32 is connected to an electric motor 72 by abelt 74, such that all of the wheels 30 can drive and/or be driven bythe electric motor 72. By utilizing multiple wheels 30 to drive oneoutput shaft 32, the power output of the wheel assembly 210 may beincreased relative to a system with only one wheel 30. In otherembodiments, the wheel assembly 210 includes more or fewer wheels 30.

The wheels 30 may be fixedly coupled to the output shaft 32.Alternatively, the wheels 30 may be selectively coupled to the outputshaft 32 by a clutch, ratchet, or one-way bearing. Such a configurationmay permit the wheels 30 to rotate relative to one another. In someembodiments, a first wheel 30 may be coupled to the output shaft 32after a second wheel 30 has already begun rotating, such that themomentum of the second wheel 30 imparts a torque on the first wheel 30,facilitating rotation of the first wheel 30. Such a configuration may beused to facilitate startup of rotation of the first wheel 30.

The system 200 further includes a second subassembly, shown as wheelassembly 220. The wheel assembly 220 includes one wheel 30 is coupled toan output shaft 32. The output shaft 32 is rotatably supported by a base20. The wheel 30 is directly coupled to the output shaft 32 such thatthe wheel 30 rotates about an axis 34. The wheel 30 is driven by aweight actuator 50 that repositions one or more weights 40 relative tothe wheel 30. The moment load of the weights 40 on the wheel 30 drivesthe output shaft 32. The output shaft 32 is connected to an electricmotor 72 by a belt 74, such that the wheel 30 can drive and/or be drivenby the electric motor 72.

In some embodiments, the electric motors 72 of the wheel assembly 210and the wheel assembly 220 are both electrically coupled to a common setof batteries 76 (e.g., selectively coupled as controlled by thecontroller 110). Accordingly, the electric motors 72 may each receiveelectrical energy from the batteries 76 and/or supply electrical energyto the batteries 76. In some embodiments, the electrical energy from onewheel assembly may be used to drive the other wheel assembly. By way ofexample, the wheel assembly 210 may be operating at a high speed whilethe wheel assembly 220 is stationary or operating at a low speed. Theelectric motor 72 of the wheel assembly 210 may provide electricalenergy that is supplied to the electric motor 72 of the wheel assembly220 to drive the wheel 30 of the wheel assembly 220. Such aconfiguration may be used to facilitate startup of one of the wheelassemblies.

Referring to FIG. 9 , a power transmission system, wheel assembly, powertransmission assembly, power transmission, power conversion assembly, orgenerator, is shown as system 300. The system 300 represents onepossible arrangement of the generic system 10. Accordingly, anydescription with reference to the system 10 may apply to the system 300,except as otherwise stated.

The weights 40 of the system 300 include a plurality of weights 302.Each of the weights 302 forms a discrete piece that is selectivelycoupled to the wheel 30. As shown, the system 300 includes elevenweights 302. In other embodiments, the system 300 includes more or fewerweights 302. As shown, the weights 302 are positioned along acircumference of the wheel 30. In some embodiments, the weights 302 arerigid. In other embodiments, the weights 302 are flexible. By way ofexample, the weights 302 may bend into a concave shape when insertedinto a track that extends along the circumference of the wheel 30.

The weights 302 may be shaped to facilitate densely packing the weights302 with few gaps between the weights 302. As shown, the weights 302 areshaped as trapezoidal prisms that extend along the axis 34. Adjacentsurface of the weights 302 engage one another, minimizing gaps betweenthe weights 302 and maximizing the mass that can be supported by thewheel 30. In other embodiments, the weights 302 are otherwise shaped. Byway of example, the weights 302 be shaped as triangular prisms that eachhave a triangular cross section. In such an embodiment, adjacentsurfaces of the weights 302 may engage one another, similarly to thetrapezoidal weights 302 of FIG. 9 . By way of another example, theweights 302 may have a rectangular cross section. In some suchembodiments, the weights 302 are flat plates that can be packed closelyto one another. By way of another example, the weights 302 may havecircular or other shaped cross sections. In some embodiments, the system300 includes weights having a variety of different shapes (e.g., weights302 with triangular cross sections positioned between weights 302 withrectangular cross sections).

The weights 302 may be selectively coupled to the wheel 30 such that theweights 302 may be decoupled from the wheel 30 when the weights 302reach the subtraction position 60. As shown, the system 300 includes aplurality of couplers 304 that selectively couple (e.g., selectivelyrotatably couple, selectively fixedly couple, etc.) one or more of theweights 302 to the wheel 30. The controller 110 may control the couplers304 to decouple the corresponding weights 302 from the wheel 30 when theweight 302 reaches the subtraction position 60. The system 300 mayinclude one coupler 304 that couples each of the weights 302 to thewheel 30. In other embodiments, each coupler 304 couples multipleweights 302 to the wheel 30. In some embodiments, the coupler 304includes an electromagnet that may be activated to magnetically coupleone or more weights 302 to the wheel 30. In some embodiments, thecoupler 304 includes a suction port coupled to a vacuum pump thatapplies suction to couple one or more weights to the wheel 30. In someembodiments, the coupler 304 includes a clutch, latch, grabber,solenoid, or other device that mechanically engages one or more weights302 to couple the one or more weights 302 to the wheel 30.

In some embodiments, the weights 302 are otherwise selectively coupledto the wheel 30. By way of example, the system 300 may include a trackthat surrounds a portion of the wheel 30 extending between the additionposition 64 and the subtraction position 60. A weight 302 may be droppedinto a recess defined by the wheel 30 at the addition position 64. Therecess may extend radially outward such that the weight 302 is capturedwithin the recess and prevented from moving along the circumference ofthe wheel. As the wheel 30 rotates, the wheel 30 may force the weight302 into engagement with the track, which prevents the weight 302 fromexiting the recess. The track may end immediately before the subtractionposition 60 such that the weight 302 is permitted to exit the recess atthe subtraction position 60 due to the force of gravity.

Referring still to FIG. 9 , the weight actuator 50 includes a movablestructure or rotating structure, shown as arm 310. The arm 310 iscoupled to at least one actuator or lift, shown as motor 312, that isconfigured to control motion of the arm 310. As shown, the motor 312controls rotation of the arm 310 about an axis of rotation that extendssubstantially parallel to the axis 34. Additionally or alternatively,the motor 312 may control translational movement, articulation (e.g.,bending), and/or telescoping (i.e., a change in length) of the arm 310.Positioned at the end of the arm 310 is an interface (e.g., anelectromagnet, a claw or grabber, a vacuum, etc.), shown as end effector314, that is configured to selectively couple the weight 302 to the arm310. In operation, the end effector 314 engages each weight 302 afterthe weight 302 has reached the subtraction position 60. The motor 312then causes the arm 310 to raise the weight 302 to an elevated position.With the weight 302 in the elevated position, the end effector 314disengages the weight 302 from the arm 310, permitting the weight 302 tobe coupled to the wheel 30 at the addition position 64 (e.g., by thecoupler 304). In some embodiments, the arm 310 and/or the end effector314 are configured to rotate the weights 302 to facilitate depositingthe weights 302 in the alignment position 64 with the weights 302 in adesired orientation.

As shown in FIG. 9 , the system 300 includes an electrical energygenerator, energy capturer, or recovery platform, shown as recovery mat320. The recovery mat 320 is positioned below the subtraction position60 such that the weights 302 fall onto the recovery mat 320 afterdecoupling from the wheel 30. Accordingly, the recovery mat 320experiences the impact force from the falling weight 302. The recoverymat 320 compresses or deflects below the weight 302, receiving thekinetic energy from the weight 302 and slowing the weight 302 to a stop.The weight actuator 50 may then recover the weight 302 from atop therecovery mat 320 and move the weight 302 to the elevated position. Inother embodiments, the recovery mat 320 is omitted.

The recovery mat 320 may be configured to convert a portion of thekinetic energy from the falling weight 302 to electrical energy. By wayof example, the recovery mat 320 may include a platform positioned alonga top surface of the recovery mat 320 that is configured to movevertically. The platform may be coupled to one or more electric motorsor generators, such that movement of the platform drives the electricmotors to provide electrical energy. The electrical energy provided bythe electric motors may be used to power other components of the system300 (e.g., to drive the weight actuator 50, to charge the batteries 76,etc.). The force of the weight 302 may drive the platform downward,thereby driving the electric motors. After the weight 302 has beenremoved from the recovery mat 320, the motors may drive the platformupward to reset the position of the platform. In one example, theplatform is supported by one or more linear actuators, and the linearactuators are coupled to the motor. Accordingly, the linear actuatorsmay couple the movement of the platform to the movement of the electricmotors.

Referring still to FIG. 9 , the system 300 further includes a holdingbay, holding area, hopper, or staging assembly, shown as hopper assembly350. The hopper assembly 350 temporarily stores the weights 302 afterthe weights 302 are raised by the weight actuator 50 until the weights302 are coupled to the wheel 30. The hopper assembly 350 facilitatesimmediate introduction of the weights 302 to the wheel 30 regardless ofthe position of the arm 310. As shown, the hopper assembly 350 includesa hopper body 352 that defines a passage 354 that receives and containsone or more of the weights 302. The weight actuator 50 deposits theweights 302 at a first end of the passage 354, and the weights 302 exitan opposing, second end of the passage 354 to be introduced back to thewheel 30 at the addition position 64. An actuator assembly, shown ashopper index actuator 356, is coupled to the hopper body 352 adjacentthe second end of the passage 354. The hopper index actuator 356includes an index wheel that engages the weights 302 within the passage354 that is driven by an electric motor. With the hopper index actuator356 stationary, the hopper index actuator 356 prevents the weights 302from exiting the passage 354. The hopper index actuator 356 may bedriven to dispense a weight 302 onto the wheel 30. In other embodiments,the hopper assembly 350 is omitted, and the weight actuator 50 moves theweights 302 directly onto the wheel 30 at the addition position 64.

In some embodiments, the arm 310 is configured to move along a path thatutilizes the momentum of the weights 302 caused by motion of the wheel30. By way of example, a weight 302 at the subtraction position 60 mayhave momentum that would continue to carry the weight 302 horizontallyaway from the wheel 30. The path of the arm 310 after the end effector314 engages the weight 302 may initially move the weight 302 in thefirst direction, such that the momentum 302 of the weight 302 moves theweight 302 along the path without any energy being consumed by the motor312. When the momentum has been depleted, the motor 312 may begin todrive the arm 310 to complete the movement of the weight 302 to thehopper assembly 350 or the addition position 64.

Referring to FIG. 10 , a power transmission system, wheel assembly,power transmission assembly, power transmission, power conversionassembly, or generator, is shown as system 400. The system 400represents one possible arrangement of the generic system 10.Accordingly, any description with reference to the system 10 may applyto the system 400, except as otherwise stated.

The system 400 includes a weight 402. The weight 402 is a discrete piecethat is slidably coupled to the wheel 30. Specifically, the system 400includes a guide, slide, or track, shown as track 404, that is coupled(e.g., fixedly coupled) to the wheel 30. The track 404 is slidablycoupled to the weight 402 (e.g., by one or more bushings or bearings)such that the weight 402 moves along a path P defined by the track 404.As shown, the path P is centered about the track 404 and extends alongthe track 404. Accordingly, the weight 402 is selectively repositionablerelative to the wheel 30 about along the track 404.

The weight actuator 50 of the system 400 includes an actuator (e.g., anelectric motor, an electric linear actuator, etc.), shown as weightactuator 406, that is configured to move the weight 402 along the track404. The weight actuator 406 is coupled to the wheel 30 and the weight402. By way of example, the weight actuator 406 may include a linearactuator that is coupled to the weight 402 and configured to repositionthe weight 402 along the track 404. By way of another example, theweight actuator 406 may drive a belt or a rack gear that is fixedlycoupled to the weight 402 such that the weight 402, thereby driving theweight 402 along the track 404.

As shown in FIG. 10 , the track 404 extends perpendicular to the outputshaft 32, and the track 404 is aligned with the output shaft 32.Accordingly, the path P of the weight 402 intersects the axis 34 of thewheel 30. The weight 402 travels radially relative to the axis 34 as theweight 402 moves along the path P. Accordingly, as the weight 402travels along the path P, the distance between the weight 402 and theaxis 34 varies, changing the moment of inertia of the weight 402 aboutthe axis 34. As shown, the track 404 extends on both sides of the outputshaft 32. Accordingly, as the weight 402 moves along the track 404, themoment of inertia of the weight 402 decreases as the weight 402 movestoward the axis 34, then increases as the weight 402 moves beyond theaxis 34. In other embodiments, the path of the weight 402 extends ononly one side of the axis 34.

In operation, the weight 402 may begin in the addition position 64 withthe weight 402 located at a first end of the path P, such that thegravitational force on the weight 402 drives the weight 402 and thewheel 30 to rotate about the axis 34 (e.g., counterclockwise as shown inFIG. 10 ). When the weight 402 reaches the subtraction position 60(e.g., reaches a predetermined positions, reaches a predetermined rangeof positions, etc.), the controller 110 activates the weight actuator406 to move the weight 402 along the track 404 toward the axis 34. Thisreduces the moment load of the force of gravity on the weight 402 thatwould oppose counterclockwise movement of the wheel 30. In embodimentswhere the path P and the track 404 extend on both sides of the axis 34,such as the embodiment of FIG. 10 , the controller 110 may control theweight actuator 406 to continue moving the weight 402 beyond the axis34, toward the second end of the path P, where the gravitational forceon the weight 402 again drives the weight 402 and the wheel 30 to rotatecounterclockwise. In embodiments where the path P and the track 404extends on only one side of the axis 34, the controller 110 may controlthe weight actuator 406 to retain the weight 402 as close to the axis 34possible (e.g., near the axis 34, at the axis 34). In this position, themoment load of the force of gravity on the weight 402 that would opposecounterclockwise movement of the wheel 30 is minimized as the wheel 30continues to rotate (e.g., due to momentum, due to the effect of otherweights 402, due to an input from the electric motor 72, etc.). Once thewheel 30 has rotated sufficiently for the first end of the path P toapproach (e.g., fall within a threshold range of positions relative to)the addition position 64, the controller 110 may control the weightactuator 406 to return the weight 402 to the first end of the path P,where the gravitational force on the weight 402 again drives the wheel30 to rotate clockwise.

In other embodiments, the system 400 includes multiple weights 402. Byway of example, the system 400 may include multiple tracks 404, eachtrack 404 supporting a different weight 402. The tracks 404 may havediffering lengths. By way of example, the system 400 may include onetrack 404 that extends across the axis 34 and two additional tracks 404that extend on only one side of the axis 34. The movement of each weight402 may be controlled individually by a corresponding weight actuator406.

Referring to FIG. 11 , a power transmission system, wheel assembly,power transmission assembly, power transmission, power conversionassembly, or generator, is shown as system 500. The system 500represents one possible arrangement of the generic system 10.Accordingly, any description with reference to the system 10 may applyto the system 500, except as otherwise stated.

The weights 40 of the system 500 include volumes of flowable materialthat are held within containers coupled to the wheel 30. As used herein,the term “flowable material” can refer to any collection of molecules,particles, elements, or objects that are capable of flowing into acontainer. A flowable material can include liquids, solids, or acombination thereof. By way of example, the flowable material mayinclude materials that are liquid at room temperature and atmosphericpressure, such as water, mercury, oil, or alcohol. The flowable materialmay include bulk solids, granules, grains, balls, pellets, fragments,pieces, powders, or other flowable forms of materials that are solid atroom temperature and atmospheric pressure. By way of example, theflowable material may include sand, soil, gravel, metal balls or powders(e.g., lead pellets, steel ball bearings, steel cubes, iron powder,etc.), salt, grains (e.g., corn, rice, etc.), sugar, plastic pellets, orglass beads.

Referring still to FIG. 11 , the system 500 includes a plurality ofcontainers, compartments, or vessels (e.g., buckets, cups, tanks, etc.),shown as buckets 502 that are coupled to the wheel 30. Although thebuckets 502 are shown as being square, the buckets 502 may be otherwiseshaped, (e.g., triangular, rectangular, spherical, cylindrical, etc.).Each bucket 502 defines a volume or recess. As shown, each bucket 502 isrotatably coupled to the wheel 30 such that the buckets 502 maintain asubstantially constant orientation relative to the direction of gravityas the wheel 30 rotates. As shown, coupled to the bottom of each bucket502 is a valve or release, shown as a pair of doors 504, that areselectively repositionable relative to the bucket 502. In a closedconfiguration (e.g., as shown in the uppermost bucket 502 of FIG. 11 ),the doors 504 seal against the bucket 502, preventing flowable materialfrom exiting the bucket 502. In an open configuration (e.g., as shown inthe lowermost bucket 502 of FIG. 11 ), the doors 504 open to permit theflowable material to leave the bucket 502 through an aperture defined atthe bottom of the bucket 502.

During operation, the buckets 502 are filled with a volume 506 offlowable material when in the addition position 64. In some embodiments,the volume 506 is a predetermined amount of flowable material. Theweight of the volume 506 of flowable material forces the bucket 502downward, driving rotation of the wheel 30 (e.g., counterclockwise asshown in FIG. 11 ). When the bucket 502 reaches the subtraction position60, an actuator (e.g., a latch, one or more linear actuators, etc.),shown as door actuator 508, moves the doors 504 of the bucket 502 to theopen configuration, permitting the volume 506 of flowable material tofall into a container, vessel, holding bay, or tank, shown as bottomtank 510. In some embodiments, the door actuator 508 is operated by thecontroller 110 (e.g., using electronic signals). In other embodiments,the door actuator 508 is mechanically actuated (e.g., the door actuator508 engages a protrusion coupled to the base 20 when the wheel 30reaches a predetermined position, causing the door actuator 508 to openthe doors 504.). In some embodiments, the bottom tank 510 is offset tothe left as shown in FIG. 11 to ensure that any flowable materialdispensed prior to the bucket 502 entering the subtraction position 60is captured. After the volume 506 has been emptied from the bucket 502,the door actuator 508 closes the doors 504, and the bucket 502 movesback toward the addition position 64. Alternatively, the door actuator508 may open the doors 504 while the bucket 502 is between thesubtraction position 60 and the addition position 64, or while thebucket 502 is at the addition position 64.

In some embodiments, each bucket 502 includes an actuated pushingmechanism (e.g., a plunger) that actively forces the flowable materialout of the bucket 502 and into the bottom tank 510. The pushingmechanism may dispense the flowable material more quickly than gravity,which may facilitate faster rotation speeds of the wheel 30. The pushingmechanism may also be configured to displace a consistent amount offlowable material each time (e.g., by controlling the stroke length ofthe pushing mechanism). In some embodiments, the amount of flowablematerial dispensed is configured to completely empty the bucket 502.

The bottom tank 510 contains a volume 512 of flowable material. Thevolume 512 may be larger than the volume 506. In the system 500, theweight actuator 50 includes an elevator, lift, or actuator, shown aspump 520, that is fluidly coupled to the bottom tank 510 and to aconduit (e.g., a pipe, tube, hose, etc.), shown as pipe 522. The pump520 is configured to drive a portion of the flowable material from thevolume 512 within the bottom tank 510, through the pipe 522, to acontainer, vessel, holding bay, or tank, shown as top tank 524, that isfluidly coupled to the pipe 522. The pump 520 may be powered byelectrical energy from the electric motor 72 and/or the battery 76. Insome embodiments, the system 500 utilizes multiple pumps 520 (e.g., inseries, in parallel).

The top tank 524 contains a volume 526 of the flowable material. The toptank 524 is fluidly coupled to a dispenser, shown as fill valve 528. Thefill valve 528 is configured to control a flow of material from the toptank 524 into the buckets 502. In some embodiments, the fill valve 528is configured to dispense a predetermined amount (e.g., a predeterminedvolume, a predetermined mass, etc.) of the flowable material into eachbucket 502. In some embodiments, the fill valve 528 forms a seal witheach bucket 502 when the bucket 502 is in the addition position 64 tominimize spillage of the flowable material while the bucket 502 is beingfilled. By way of example, the bucket 502 may include a door that openswhen the fill valve 528 is in close proximity to the bucket 502, and thefill valve 528 may form a seal with the door. In some embodiments, thefill valve 528 includes an actuated pushing mechanism (e.g., a plunger)that actively forces the flowable material into the bucket 502. Thepushing mechanism may dispense the flowable material more quickly thangravity, which may facilitate faster rotation speeds of the wheel 30.The pushing mechanism may also be configured to displace a consistentamount of flowable material each time (e.g., by controlling the strokelength of the pushing mechanism). In some embodiments, the amount offlowable material dispensed is configured to completely fill each bucket502.

In other embodiments, the buckets 502 are fixedly coupled to the wheel30, such that the buckets 502 rotate with the wheel 30. In suchembodiments, the flowable material may automatically be poured from thebuckets 502 when the buckets 502 near the subtraction position 60, asthe rotation of the wheel 30 inverts the buckets 502. In suchembodiments, the doors 504 and/or the door actuators 508 may be omitted.In other embodiments, another type of elevator is utilized to move theflowable material from the bottom tank 510 to the top tank 524. By wayof example, the elevator may include one or more buckets or containerscoupled to a conveyor. The conveyor drives the buckets along a path suchthat the buckets scoop the flowable material from the bottom tank 510and pour the flowable material into the top tank 524.

In other embodiments, the system 500 includes a conveyor or elevator(e.g., driven by pulleys and/or gears) that exchanges the bottom tank510 with the top tank 524 after the bottom tank 510 is filled. By way ofexample, the conveyor may raise the bottom tank 510 above the wheel 30such that the fill valve 528 dispenses flowable material from the bottomtank 510. By way of another example, the conveyor may lower the top tank524 below the wheel 30 to receive the flowable material from the buckets502. In some embodiments, additional tanks are introduced into thisrotation to form a queue of tanks that are ready to be swapped intoposition above or below the wheel 30. This may reduce any potentialspillage of flowable material while the tanks are being exchanged.

Referring to FIGS. 12 and 13 , a power transmission system, wheelassembly, power transmission assembly, power transmission, powerconversion assembly, speed governor, or energy storage device,generator, is shown as system 600, according to an exemplary embodiment.The system 600 may be substantially similar to the system 10, except asotherwise specified herein.

The system 10 includes a chassis, frame, or base assembly, shown as base602, configured to support the other components of the system 600. Thebase 602 defines an aperture that receives a shaft support shaft, shownas output shaft 604. A series of wheels, rotating frames, or rotatingsupport structures, shown as wheels 606, are coupled (e.g., fixedlycoupled, selectively coupled by one or more clutches, etc.) to theoutput shaft 604. The output shaft 604 and the wheels 606 rotate aboutan axis of rotation, shown as axis 608. The axis 608 extends along theoutput shaft 604 (e.g., is centered about the output shaft 604). In someembodiments, the axis 608 extends substantially vertically. In suchembodiments, the wheels 606 each rotate within a substantiallyhorizontal plane (e.g., a plane perpendicular to the axis 608). In otherembodiments, the axis 608 is otherwise oriented. By way of example, theaxis 608 may extend substantially horizontally. In such embodiments, thewheels 606 each rotate within a substantially vertical plane (e.g., aplane perpendicular to the axis 608).

The output shaft 604 is coupled to an electromagnetic device ormotor/generator, shown as electric motor 610. The electric motor 610 iselectrically coupled to an energy storage device (e.g., batteries,capacitors, etc.), shown as batteries 612. In some configurations, theoutput shaft 604 drives the electric motor 610 to produce electricalenergy that is stored within the batteries 612. In other configurations,the electric motor 610 receives electrical energy from batteries 612 anddrives the output shaft 604. The output shaft 602 is further coupled toa speed sensor or rotation sensor (e.g., an optical encoder), shown asrotation sensor 630. The rotation sensor 630 is configured to providesensor data indicative of a rotational speed of the output shaft 602and/or the wheels 606.

The system 600 includes a series of sliding weight assemblies 620coupled to each wheel 606. FIG. 12 illustrates the arrangement of thesliding weight assemblies 620 on the uppermost wheel 606, although itshould be understood that each of the wheels 606 may have a similararrangement. Each sliding weight assembly 620 includes a weight 622 thatis slidably coupled to a guide, shown as track 624. The tracks 624 areeach coupled to one of the wheels 606. The tracks 624 are each orientedextending radially outward relative to the axis 608. The weights 622 arerepositionable along the length of each track 624 between an outermostposition (shown in solid lines in FIG. 12 ) and an innermost position(shown in dashed lines in FIG. 12 ). The weights 622 are moved along thetracks 624 by an actuators (e.g., an electric motor driving a belt orrack gear, an electric linear actuator, etc.), shown as weight actuators626. The weight actuators 626 may be powered by the batteries 612.Operation of the electric motor 610, the batteries 612, and the weightactuators 626 may be controlled by a controller (e.g., the controller110). The controller may control these functions based on sensor datafrom the rotation sensor 630.

During operation, the weights 622 begin in their outermost positions,and the wheels 606 are driven to a starting speed by the electric motor610, at which point the system 600 contains an initial amount of kineticenergy. The kinetic energy may be used to perform one or more functions(e.g., to drive a PTO similar to the PTO 70, to drive the electric motor610 to generate electric energy, due to frictional losses, etc.). As thekinetic energy in the system 600 decreases, the wheels 606 begin torotate more slowly. In response to a decrease in speed of the wheels 606(e.g., as sensed by the rotation sensor 630), the weight actuators 626drive the weights 622 toward the innermost positions. This decreases themoment of inertia of the system 600, increasing the speed of the wheels606 until a desired speed (e.g., the starting speed). A controller mayrepeat this process until all of the weights 622 are at the innermostpositions. At this point, the electric motor 610 may drive the wheels606 to maintain the desired speed, and the weight actuators 626 mayreturn the weights 622 to the outermost positions.

In some embodiments, all of the weights 622 move toward the axis 608 inunison. In other embodiments, a first subset of the weights 622initially move toward the axis 608, and a second subset of the weights622 begin moving toward the axis 608 after the first subset reach theinnermost positions. In some embodiments, each sliding weight assembly620 includes multiple weights 622 positioned on each track 624 (e.g., 2,3, 4, 5, 6, 7, or more weights 622). Once one of the weights 622 reachesthe innermost position, the next weight 622 may begin moving toward theaxis 608. This process may repeat for each weight 622.

In some embodiments, each wheel 606 has a relatively large diameter tofacilitate an extended travel of the weights 622. By way of example, thewheels 606 may be 25 ft, 50 ft, 100 ft 1000 ft, 5000 ft or greater indiameter. The heights of the wheels 606 may be relatively small tofacilitate stacking multiple wheels 606. In some embodiments, the system600 includes more or fewer wheels 606 (e.g., 1, 2, 4, 5, 6, 7, 8, 9, 10,15, 20, 30, 50, 100, or more wheels 606). In some embodiments, theoutput shaft 604 is coupled to multiple electric motors 610. In someembodiments, the output shaft 604 is coupled to the electric motors 610through a power transmission (e.g., a gear train).

In some embodiments, it is advantageous to minimize the weight of thewheels 606 and the output shaft 604 and maximize the weight of theweights 622. This arrangement maximizes the amount of output powerprovided by the system 600 for weights 622 of a given size whileminimizing the energy required to accelerate the wheels 606. In someembodiments, the wheel 606 includes relatively lightweight materials,such as aluminum or bamboo. In some embodiments, the weights 622 includerelatively dense materials, such as lead, mercury, steel, or iron.

In some embodiments, the tracks 624 and/or the weights 622 include aratchet assembly that selectively prevents outward movement of theweights 622. Such a ratchet assembly may apply an inward force on theweights 622 to limit outward movement of the weights 622 duringrotation. The ratchet assembly may be released to permit the weights 622to return to their outermost positions (e.g., automatically due torotation of the system 600, without the application of any energy by theweight actuators 626).

As utilized herein, the terms “approximately,” “about,” “substantially,”and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the disclosure as recited inthe appended claims.

It should be noted that the term “exemplary” and variations thereof, asused herein to describe various embodiments, are intended to indicatethat such embodiments are possible examples, representations, orillustrations of possible embodiments (and such terms are not intendedto connote that such embodiments are necessarily extraordinary orsuperlative examples).

The term “coupled” and variations thereof, as used herein, means thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent or fixed) or moveable (e.g.,removable or releasable). Such joining may be achieved with the twomembers coupled directly to each other, with the two members coupled toeach other using a separate intervening member and any additionalintermediate members coupled with one another, or with the two memberscoupled to each other using an intervening member that is integrallyformed as a single unitary body with one of the two members. If“coupled” or variations thereof are modified by an additional term(e.g., directly coupled), the generic definition of “coupled” providedabove is modified by the plain language meaning of the additional term(e.g., “directly coupled” means the joining of two members without anyseparate intervening member), resulting in a narrower definition thanthe generic definition of “coupled” provided above. Such coupling may bemechanical, electrical, or fluidic.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below”) are merely used to describe the orientation of variouselements in the FIGURES. It should be noted that the orientation ofvarious elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

The hardware and data processing components used to implement thevarious processes, operations, illustrative logics, logical blocks,modules and circuits described in connection with the embodimentsdisclosed herein may be implemented or performed with a general purposesingle- or multi-chip processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. A generalpurpose processor may be a microprocessor, or, any conventionalprocessor, controller, microcontroller, or state machine. A processoralso may be implemented as a combination of computing devices, such as acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. In some embodiments, particularprocesses and methods may be performed by circuitry that is specific toa given function. The memory (e.g., memory, memory unit, storage device)may include one or more devices (e.g., RAM, ROM, Flash memory, hard diskstorage) for storing data and/or computer code for completing orfacilitating the various processes, layers and modules described in thepresent disclosure. The memory may be or include volatile memory ornon-volatile memory, and may include database components, object codecomponents, script components, or any other type of informationstructure for supporting the various activities and informationstructures described in the present disclosure. According to anexemplary embodiment, the memory is communicably connected to theprocessor via a processing circuit and includes computer code forexecuting (e.g., by the processing circuit or the processor) the one ormore processes described herein.

The present disclosure contemplates methods, systems and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, orother optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Combinationsof the above are also included within the scope of machine-readablemedia. Machine-executable instructions include, for example,instructions and data which cause a general purpose computer, specialpurpose computer, or special purpose processing machines to perform acertain function or group of functions.

Although the figures and description may illustrate a specific order ofmethod steps, the order of such steps may differ from what is depictedand described, unless specified differently above. Also, two or moresteps may be performed concurrently or with partial concurrence, unlessspecified differently above. Such variation may depend, for example, onthe software and hardware systems chosen and on designer choice. Allsuch variations are within the scope of the disclosure. Likewise,software implementations of the described methods could be accomplishedwith standard programming techniques with rule-based logic and otherlogic to accomplish the various connection steps, processing steps,comparison steps, and decision steps.

It is important to note that the construction and arrangement of thesystem 10 as shown in the various exemplary embodiments is illustrativeonly. Additionally, any element disclosed in one embodiment may beincorporated or utilized with any other embodiment disclosed herein. Forexample, the wheel assembly 210 of FIG. 8 may include both the system300 of FIG. 9 and the system 400 of FIG. 10 . Although only one exampleof an element from one embodiment that can be incorporated or utilizedin another embodiment has been described above, it should be appreciatedthat other elements of the various embodiments may be incorporated orutilized with any of the other embodiments disclosed herein.

What is claimed is:
 1. A power transmission assembly, comprising: abase; a frame rotatably coupled to the base and configured to rotateabout an axis; an output shaft coupled to the frame; a weightrepositionable relative to the frame; and a weight actuator configuredto reposition the weight relative to the frame to move the weight from afirst position located at a first height to a second position located ata second height, wherein the second height is greater than the firstheight such that a gravitational force on the weight drives the frame torotate about the axis and drive the output shaft; wherein the weight isa volume of flowable material, further comprising a container coupled tothe frame and configured to receive the volume of flowable material. 2.The power transmission assembly of claim 1, wherein the flowablematerial includes a liquid.
 3. The power transmission assembly of claim1, wherein the flowable material includes a solid.
 4. A powertransmission assembly, comprising: a base; a frame rotatably coupled tothe base and configured to rotate about an axis; an output shaft coupledto the frame; a weight repositionable relative to the frame; and aweight actuator configured to reposition the weight relative to theframe to move the weight from a first position located at a first heightto a second position located at a second height, wherein the secondheight is greater than the first height such that a gravitational forceon the weight drives the frame to rotate about the axis and drive theoutput shaft; wherein the weight actuator is configured to move theweight to a position in which the axis intersects the weight.
 5. A powertransmission assembly, comprising: a base; a frame rotatably coupled tothe base and configured to rotate about an axis; an output shaft coupledto the frame; a weight repositionable relative to the frame; and aweight actuator configured to reposition the weight relative to theframe to move the weight from a first position located at a first heightto a second position located at a second height, a first electromagneticdevice coupled to the output shaft; a second frame; a secondelectromagnetic device coupled to the second frame; and a second weightrepositionable relative to the second frame; wherein the firstelectromagnetic device is configured to provide electrical energy to thesecond electromagnetic device such that the second electromagneticdevice drives rotation of the second frame; wherein the second height isgreater than the first height such that a gravitational force on theweight drives the frame to rotate about the axis and drive the outputshaft; wherein the frame is a first frame and the weight is a firstweight.
 6. A power transmission assembly, comprising: a base; a framerotatably coupled to the base and configured to rotate about an axis; anoutput shaft coupled to the frame; a weight repositionable relative tothe frame; and a weight actuator configured to reposition the weightrelative to the frame to move the weight from a first position locatedat a first height to a second position located at a second height,wherein the second height is greater than the first height such that agravitational force on the weight drives the frame to rotate about theaxis and drive the output shaft; wherein the weight actuator is a firstweight actuator, further comprising a second weight actuator configuredto reposition the second weight relative to the second frame.
 7. A powertransmission assembly, comprising: a base; a frame rotatably coupled tothe base; an output shaft coupled to the frame; a first containercoupled to the frame, the first container being movable between a raisedposition and a lowered position; a second container; and an actuatorconfigured to transfer a volume of flowable material from the secondcontainer to the first container when the first container is in theraised position, wherein the first container is positioned such that agravitational force on the volume of flowable material drives rotationof the output shaft as the first container moves from the raisedposition to the lowered position; and wherein the first container isconfigured to deposit the volume of flowable material into the secondcontainer in response to the first container reaching the loweredposition.